OverviewDefensive linemen will dominate the first round, both tackles and ends. As many as six defensive tackles could hear their names called in the top 32 picks, and several other pass rushers will go in the first round too. Florida’s Sharrif Floyd and Utah’s Star Lotulelei are the top tackles.Cowboys’ needsWith the Cowboys switching to the 4-3, all four linemen have new positions. DeMarcus Ware and Anthony Spencer are moving from outside linebackers to defensive ends. Ware, who turns 31 this summer, had an injury-plagued 2012 season, which was followed by off-season shoulder surgery. In the last eight games, when he had right shoulder and right elbow injuries, Ware had only two sacks. He finished with 11.5. The Cowboys opted to franchise Spencer for a second consecutive season and are paying him $10.6 million. He had his best season in 2012 with 106 tackles and 11 sacks. Jay Ratliff and Jason Hatcher are penciled in at defensive tackle. But the Cowboys could draft another tackle early with Josh Brent not expected to play in 2013, Hatcher a free agent in 2013 and Ratliff having had declining production because of injuries. Ratliff and Hatcher could rotate at the 3-technique, with a newcomer at the 1-technique.Top three DEs Ezekiel Ansah, BYU, 6-5, 271, 4.56: The Ghana native has little football experience but still made 62 tackles, 13 tackles for loss and 4.5 sacks last season in the first nine starts of his career. Bjoern Werner, Florida State, 6-3, 266, 4.81: In two seasons, he had 35 tackles for loss, 23.5 sacks, 18 passes defensed, three forced fumbles and two fumble recoveries. Datone Jones, UCLA, 6-4, 283, 4.75: He had 57 tackles, 17.5 for loss, with six sacks in 2012.Top three DTs Sharrif Floyd, Florida, 6-3, 297, 4.87: In 37 career games, including 26 starts, he had 115 tackles, 26 for loss, 4.5 sacks, three blocked field goals and a forced fumble. Star Lotulelei, Utah, 6-3, 311, 5.34: He was diagnosed with a heart condition at the scouting combine, but he had 42 tackles, 11 for loss, and five sacks in 2012. Sheldon Richardson, Missouri, 6-3, 294, 4.96: He had 75 tackles, 10.5 for loss, with four sacks, three forced fumbles and a blocked kick.Sleeper David Bass, DE, Missouri Western, 6-4, 262, 4.74: He dominated in Division II with 56 tackles for loss and 39.5 sacks in his 50-game career.Top Texas ties Damontre Moore, DE, Texas A&M, 6-5, 250, 4.84: His draft stock has plummeted since a poor showing at the combine with only 12 reps in the bench and now is a possible second-round pick. Margus Hunt, DE, SMU, 6-8, 277, 4.53: The Estonia native hasn’t played much football, but scouts are intrigued enough, especially with his 17 blocked kicks, to make him an early second-day prospect. Alex Okafor, DE, Texas, 6-5, 264, 4.89: He is a likely second-round pick after having 12 sacks and 20 quarterback pressures last season. Stansly Maponga, DE, TCU, 6-2, 256, 4.84: He will be a late-round pick after making 26 tackles, 6.5 for loss, with four sacks.Source: Heights, weights and 40 times were compiled from NFL Draft Scout.